Measuring Food Security in the United States for More Than 25 years: History, Methods, Findings, and Opportunities.

This article sets the stage for the "25 Years of Food Security Measurement: Answered Questions and Further Research" conference, with support from the Economic Research Service of the US Department of Agriculture, by providing some history of federal food security measurement, summarizing notable findings, and reviewing selected special topics in analysis methods. The federal government uses food security surveys to monitor national progress toward reducing food insecurity and to evaluate federal nutrition assistance programs. For the monitoring purpose, there is a tension between focus (on a single authoritative measurement approach) and breadth (encompassing multiple tools or instruments suitable for diverse populations, contexts, and applications). For the program evaluation purpose, challenges include coordination with study designs capable of real causal estimation in the face of strong self-selection effects and tailored reference periods in survey questions that match the timing of program participation. Some analysis methods treat the food security survey items as distinct experiences of hardship, whereas others treat the food security survey items as windows on an underlying latent variable, a food insecurity score. The severity of food-related hardship may be assessed quantitatively by the number of distinct hardships reported, by the estimated value of a latent food insecurity score, or by the frequency of occurrence for sentinel hardships. Ongoing work investigates statistical approaches that are sufficiently simple for policy application and yet sufficiently flexible to accurately match the empirical survey evidence.

Health Impact and Cost-Effectiveness of Achieving the National Salt and Sugar Reduction Initiative Voluntary Sugar Reduction Targets in the United States: A Microsimulation Study.

BACKGROUND: High intake of added sugar is linked to weight gain and cardiometabolic risk. In 2018, the US National Salt and Sugar Reduction Initiative proposed government-supported voluntary national sugar reduction targets. This intervention's potential effects and cost-effectiveness are unclear. METHODS: A validated microsimulation model, CVD-PREDICT (Cardiovascular Disease Policy Model for Risk, Events, Detection, Interventions, Costs, and Trends), coded in C++, was used to estimate incremental changes in type 2 diabetes, cardiovascular disease (CVD), quality-adjusted life-years (QALYs), costs, and cost-effectiveness of the US National Salt and Sugar Reduction Initiative policy. The model was run at the individual level, incorporating the annual probability of each person's transition between health statuses on the basis of risk factors. The model incorporated national demographic and dietary data from the National Health and Nutrition Examination Survey across 3 cycles (2011 through 2016), added sugar-related diseases from meta-analyses, and policy costs and health-related costs from established sources. A simulated nationally representative US population was created and followed until age 100 years or death, with 2019 as the year of intervention start. Findings were evaluated over 10 years and a lifetime from health care and societal perspectives. Uncertainty was evaluated in a 1-way analysis by assuming 50% industry compliance and probabilistic sensitivity analyses through a second-order Monte Carlo approach. Model outputs included averted diabetes cases, CVD events and CVD deaths, QALYs gained, and formal health care cost savings, stratified by age, race, income, and education. RESULTS: Achieving the US National Salt and Sugar Reduction Initiative sugar reduction targets could prevent 2.48 million CVD events, 0.49 million CVD deaths, and 0.75 million diabetes cases; gain 6.67 million QALYs; and save $160.88 billion net costs from a societal perspective over a lifetime. The policy became cost-effective (<150 000/QALYs) at 6 years, highly cost-effective (<50 000/QALYs) at 7 years, and cost-saving at 9 years. Results were robust from a health care perspective, with lower (50%) industry compliance, and in probabilistic sensitivity analyses. The policy could also reduce disparities, with greatest estimated health gains per million adults among Black or Hispanic individuals, lower income, and less educated Americans. CONCLUSIONS: Implementing and achieving the US National Salt and Sugar Reduction Initiative sugar reformation targets could generate substantial health gains, equity gains, and cost savings.

Health and Economic Impacts of the National Menu Calorie Labeling Law in the United States: A Microsimulation Study.

BACKGROUND: Excess caloric intake is linked to weight gain, obesity, and related diseases, including type 2 diabetes mellitus and cardiovascular disease (CVD). Obesity incidence is rising, with nearly 3 in 4 US adults being overweight or obese. In 2018, the US federal government finalized the implementation of mandatory labeling of calorie content on all menu items across major chain restaurants nationally as a strategy to support informed consumer choice, reduce caloric intake, and potentially encourage restaurant reformulations. Yet, the potential health and economic impacts of this policy remain unclear. METHODS AND RESULTS: We used a validated microsimulation model (CVD-PREDICT) to estimate reductions in CVD events, diabetes mellitus cases, gains in quality-adjusted life years, costs, and cost-effectiveness of the menu calorie labeling intervention, based on consumer responses alone, and further accounting for potential industry reformulation. The model incorporated nationally representative demographic and dietary data from National Health and Nutrition Examination Surveys 2009 to 2016; policy effects on consumer diets and body mass index-disease effects from published meta-analyses; and policy effects on industry reformulation, policy costs (policy administration, industry compliance, and reformulation), and health-related costs (formal and informal healthcare costs, productivity costs) from established sources or reasonable assumptions. We modeled change in calories to change in weight using an established dynamic weight-change model, assuming 50% of expected calorie reductions would translate to long-term reductions. Findings were evaluated over 5 years and a lifetime from healthcare and societal perspectives, with uncertainty incorporated in both 1-way and probabilistic sensitivity analyses. Between 2018 and 2023, implementation of the restaurant menu calorie labeling law was estimated, based on consumer response alone, to prevent 14 698 new CVD cases (including 1575 CVD deaths) and 21 522 new type 2 diabetes mellitus cases, gaining 8749 quality-adjusted life years. Over a lifetime, corresponding values were 135 781 new CVD cases (including 27 646 CVD deaths), 99 736 type 2 diabetes mellitus cases, and 367 450 quality-adjusted life years. Assuming modest restaurant item reformulation, both health and economic benefits were estimated to be about 2-fold larger than based on consumer response alone. The consumer response alone was estimated to be cost-saving by 2023, with net lifetime savings of $10.42B from a healthcare perspective and $12.71B from a societal perspective. Findings were robust in a range of sensitivity analyses. CONCLUSIONS: Our national model suggests that the full implementation of the US calorie menu labeling law will generate significant health gains and healthcare and societal cost-savings. Industry responses to modestly reformulate menu items would provide even larger additional benefits.

Health Impact and Cost-Effectiveness of Volume, Tiered, and Absolute Sugar Content Sugar-Sweetened Beverage Tax Policies in the United States: A Microsimulation Study.

BACKGROUND: Sugar-sweetened beverage taxes are a rapidly growing policy tool and can be based on absolute volume, sugar content tiers, or absolute sugar content. Yet, their comparative health and economic impacts have not been quantified, in particular, tiered or sugar content taxes that provide industry incentives for sugar reduction. METHODS: We estimated incremental changes in diabetes mellitus and cardiovascular disease, quality-adjusted life-years, costs, and cost-effectiveness of 3 sugar-sweetened beverage tax designs in the United States, on the basis of (1) volume ($0.01/oz), (2) tiers (<5 g of added sugar/8 oz: no tax; 5-20 g/8 oz: $0.01/oz; and >20 g/8 oz: $0.02/oz), and (3) absolute sugar content ($0.01 per teaspoon added sugar), each compared with a base case of modest ongoing voluntary industry reformulation. A validated microsimulation model, CVD-PREDICT (Cardiovascular Disease Policy Model for Risk, Events, Detection, Interventions, Costs, and Trends), incorporated national demographic and dietary data from the National Health and Nutrition Examination Survey, policy effects and sugar-sweetened beverage-related diseases from meta-analyses, and industry reformulation and health-related costs from established sources. RESULTS: Over a lifetime, the volume, tiered, and absolute sugar content taxes would generate $80.4 billion, $142 billion, and $41.7 billion in tax revenue, respectively. From a healthcare perspective, the volume tax would prevent 850 000 cardiovascular disease (95% CI, 836 000-864 000) and 269 000 diabetes mellitus (265 000-274 000) cases, gain 2.44 million quality-adjusted life-years (2.40-2.48), and save $53.2 billion net costs (52.3-54.1). Health gains and savings were approximately doubled for the tiered and absolute sugar content taxes. Results were robust for societal and government perspectives, at 10 years follow-up, and with lower (50%) tax pass-through. Health gains were largest in young adults, blacks and Hispanics, and lower-income Americans. CONCLUSIONS: All sugar-sweetened beverage tax designs would generate substantial health gains and savings. Tiered and absolute sugar content taxes should be considered and evaluated for maximal potential gains.

Cost-Effectiveness of a National Sugar-Sweetened Beverage Tax to Reduce Cancer Burdens and Disparities in the United States.

BACKGROUND: Sugar-sweetened beverage (SSB) consumption contributes to obesity, a risk factor for 13 cancers. Although SSB taxes can reduce intake, the health and economic impact on reducing cancer burdens in the United States are unknown, especially among low-income Americans with higher SSB intake and obesity-related cancer burdens. METHODS: We used the Diet and Cancer Outcome Model, a probabilistic cohort state-transition model, to project health gains and economic benefits of a penny-per-ounce national SSB tax on reducing obesity-associated cancers among US adults aged 20 years and older by income. RESULTS: A national SSB tax was estimated to prevent 22 075 (95% uncertainty interval [UI] = 16 040-28 577) new cancer cases and 13 524 (95% UI = 9841-17 681) cancer deaths among US adults over a lifetime. The policy was estimated to cost $1.70 (95% UI = $1.50-$1.95) billion for government implementation and $1.70 (95% UI = $1.48-$1.96) billion for industry compliance, while saving $2.28 (95% UI = $1.67-$2.98) billion cancer-related healthcare costs. The SSB tax was highly cost-effective from both a government affordability perspective (incremental cost-effectiveness ratio [ICER] = $1486, 95% UI = -$3516-$9265 per quality-adjusted life year [QALY]) and a societal perspective (ICER = $13 220, 95% UI = $3453-$28 120 per QALY). Approximately 4800 more cancer cases and 3100 more cancer deaths would be prevented, and $0.34 billion more healthcare cost savings would be generated among low-income (federal poverty-to-income ratio [FPIR] ≤ 1.85) than higher-income individuals (FPIR > 1.85). CONCLUSIONS: A penny-per-ounce national SSB tax is cost-effective for cancer prevention in the United States, with the largest health gains and economic benefits among low-income Americans.

Cost Effectiveness of Nutrition Policies on Processed Meat: Implications for Cancer Burden in the U.S.

INTRODUCTION: Processed meats are associated with increased risk of colorectal and stomach cancers, but health and economic impacts of policies to discourage processed meats are not well established. This paper aims to evaluate the cost effectiveness of implementing tax and warning labels on processed meats. METHODS: A probabilistic cohort-state transition model was developed in 2018, including lifetime and short-term horizons, healthcare, and societal perspectives, and 3% discount rates for costs and health outcomes. The model simulated 32 subgroups by age, gender, and race/ethnicity from the U.S. adult population and integrated nationally representative 2011-2014 data on processed meat consumption, with etiologic effects of processed meat consumption on cancer incidence, medical and indirect societal costs, and policy costs. RESULTS: Over a lifetime, the 10% excise tax would prevent 77,000 cases of colorectal cancer (95% uncertainty interval=56,800, 107,000) and 12,500 cases of stomach cancer (95% uncertainty interval=6,880, 23,900), add 593,000 quality-adjusted life years (95% uncertainty interval=419,000, 827,000), and generate net savings of $2.7 billion from a societal perspective, including $1.1 billion healthcare costs saved. The warning label policy would avert 85,400 cases of colorectal cancer (95% uncertainty interval=56,600, 141,000) and 15,000 cases of stomach cancer (95% uncertainty interval=6,860, 34,500), and add 660,000 quality-adjusted life years (95% uncertainty interval=418,000, 1,070,000), with net savings of $4.5 billion from a societal perspective, including $1.3 billion healthcare costs saved. In subgroup analyses, greater health and economic benefits accrued to (1) younger subpopulations, (2) subpopulations with greater cancer risk, and (3) those with higher baseline processed meat consumption. CONCLUSIONS: The model shows that implementing tax or warning labels on processed meats would be a cost-saving strategy with substantial health and economic benefits. The findings should encourage policy makers to consider nutrition-related policies to reduce cancer burden.

Fast Ion Transport in the Three-Dimensional Reversed-Field Pinch.

We report on the first comprehensive experimental and numerical study of fast ion transport in the helical reversed-field pinch (RFP). Classical orbit effects dominate the macroscopic confinement properties. The strongest effect arises from growth in the dominant fast ion guiding-center island, but substantial influence from remnant subdominant tearing modes also plays a critical role. At the formation of the helical RFP, neutron flux measurements indicate a drastic loss of fast ions at sufficient subdominant mode amplitudes. Simulations corroborate these measurements and suggest that subdominant tearing modes strongly limit fast ion behavior. Previous work details a sharp thermal transport barrier and suggests the helical RFP as an Ohmically heated fusion reactor candidate; the enhanced transport of fast ions reported here identifies a key challenge for this scheme, but a workable scenario is conceivable with low subdominant tearing mode amplitudes.

Greenhouse gas emissions, total food spending and diet quality by share of household food spending on red meat: results from a nationally representative sample of US households.

OBJECTIVE: To determine if US household food purchases with lower levels of red meat spending generate lower life-cycle greenhouse gas emissions (GHGE), greater nutritional quality and improved alignment with the Dietary Guidelines for Americans. Affordability of purchasing patterns by red meat spending levels was also assessed. DESIGN: Household food purchase and acquisition data were linked to an environmentally extended input-output life-cycle assessment model to calculate food GHGE. Households (n 4706) were assigned to quintiles by the share of weekly food spending on red meat. Average weekly kilojoule-adjusted GHGE, total food spending, nutrients purchased and 2010 Healthy Eating Index (HEI-2010) were evaluated using ANOVA and linear regression. SETTING: USA.ParticipantsHouseholds participating in the 2012-2013 National Household Food Acquisition and Purchase Survey. RESULTS: There was substantial variation in the share of the household food budget spent on red meat and total spending on red meat. The association between red meat spending share and total food spending was mixed. Lower red meat spending share was mostly advantageous from a nutritional perspective. Average GHGE were significantly lower and HEI-2010 scores were significantly higher for households spending the least on red meat as a share of total food spending. CONCLUSIONS: Only very low levels of red meat spending as a share of total food spending had advantages for food affordability, lower GHGE, nutrients purchased and diet quality. Further studies assessing changes in GHGE and other environmental burdens, using more sophisticated analytical techniques and accounting for substitution towards non-red meat animal proteins, are needed.

Cost-effectiveness of financial incentives for improving diet and health through Medicare and Medicaid: A microsimulation study.

BACKGROUND: Economic incentives through health insurance may promote healthier behaviors. Little is known about health and economic impacts of incentivizing diet, a leading risk factor for diabetes and cardiovascular disease (CVD), through Medicare and Medicaid. METHODS AND FINDINGS: A validated microsimulation model (CVD-PREDICT) estimated CVD and diabetes cases prevented, quality-adjusted life years (QALYs), health-related costs (formal healthcare, informal healthcare, and lost-productivity costs), and incremental cost-effectiveness ratios (ICERs) of two policy scenarios for adults within Medicare and Medicaid, compared to a base case of no new intervention: (1) 30% subsidy on fruits and vegetables ("F&V incentive") and (2) 30% subsidy on broader healthful foods including F&V, whole grains, nuts/seeds, seafood, and plant oils ("healthy food incentive"). Inputs included national demographic and dietary data from the National Health and Nutrition Examination Survey (NHANES) 2009-2014, policy effects and diet-disease effects from meta-analyses, and policy and health-related costs from established sources. Overall, 82 million adults (35-80 years old) were on Medicare and/or Medicaid. The mean (SD) age was 68.1 (11.4) years, 56.2% were female, and 25.5% were non-whites. Health and cost impacts were simulated over the lifetime of current Medicare and Medicaid participants (average simulated years = 18.3 years). The F&V incentive was estimated to prevent 1.93 million CVD events, gain 4.64 million QALYs, and save $39.7 billion in formal healthcare costs. For the healthy food incentive, corresponding gains were 3.28 million CVD and 0.12 million diabetes cases prevented, 8.40 million QALYs gained, and $100.2 billion in formal healthcare costs saved, respectively. From a healthcare perspective, both scenarios were cost-effective at 5 years and beyond, with lifetime ICERs of $18,184/QALY (F&V incentive) and $13,194/QALY (healthy food incentive). From a societal perspective including informal healthcare costs and lost productivity, respective ICERs were $14,576/QALY and $9,497/QALY. Results were robust in probabilistic sensitivity analyses and a range of one-way sensitivity and subgroup analyses, including by different durations of the intervention (5, 10, and 20 years and lifetime), food subsidy levels (20%, 50%), insurance groups (Medicare, Medicaid, and dual-eligible), and beneficiary characteristics within each insurance group (age, race/ethnicity, education, income, and Supplemental Nutrition Assistant Program [SNAP] status). Simulation studies such as this one provide quantitative estimates of benefits and uncertainty but cannot directly prove health and economic impacts. CONCLUSIONS: Economic incentives for healthier foods through Medicare and Medicaid could generate substantial health gains and be highly cost-effective.

Characterization and calibration of the Thomson scattering diagnostic suite for the C-2W field-reversed configuration experiment.

The new C-2W Thomson scattering (TS) diagnostic consists of two individual subsystems for monitoring electron temperature (Te) and density (ne): one system in the central region is currently operational, and the second system is being commissioned to monitor the open field line region. Validating the performance of the TS's custom designed system components and unique calibration of the detection system and diagnostic as a whole is crucial to obtaining high precision Te and ne profiles of C-2W's plasma. The major components include a diode-pumped Nd:YAG laser which produces 35 pulses at up to 20 kHz, uniquely designed collection lenses with a fast numerical aperture, and uniquely designed polychromators with filters sets to optimize a Te ranging from 10 eV to 2 keV. This paper describes the design principles and techniques used to characterize the main components of the TS diagnostic on C-2W, as well as the results of Rayleigh scattering calibrations performed for the whole system response.

Correlation polarimetry for broadband magnetic fluctuation measurements.

Correlation techniques have been successfully utilized for plasma diagnostics like electron cyclotron emission to reduce measurement noise. We present the first application of such a technique to Faraday-effect polarimetry measurements on the Madison Symmetric Torus (MST). The MST far infrared (FIR) interferometer-polarimeter diagnostic utilizes 11 vertical chords with a chord separation of 7-8 cm and a heterodyne detection system for fluctuation measurements up to several hundred kHz. The planar-diode mixers viewing each chord represent independent noise sources; modifying the optical setup so that two different mixers view the same chord allows cross correlation between the two independent signals to reduce the noise floor in fluctuation measurements. In this manner, the noise floor in both interferometry and polarimetry measurements in reversed-field pinch discharges has been reduced by a factor of 20-30. The correlation polarimeter provides a sensitive measurement of broadband magnetic fluctuations.

Thomson scattering systems on C-2W field-reversed configuration plasma experiment.

TAE Technologies' newly constructed C-2W experiment aims to improve the ion and electron temperatures in a sustained field-reversed configuration plasma. A suite of Thomson scattering systems has been designed and constructed for electron temperature and density profile measurements. The systems are designed for electron densities of 1 × 1012 cm-3 to 2 × 1014 cm-3 and temperature ranges from 10 eV to 2 keV. The central system will provide profile measurements of Te and ne at 16 radial locations from r = -9 cm to r = 64 cm with a temporal resolution of 20 kHz for 4 pulses or 1 kHz for 30 pulses. The jet system will provide profile measurements of Te and ne at 5 radial locations in the open field region from r = -5 cm to r = 15 cm with a temporal resolution of 100 Hz. The central system and its components have been characterized, calibrated, installed, and commissioned. A maximum-likelihood algorithm has been applied for data processing and analysis.

An upgraded interferometer-polarimeter system for broadband fluctuation measurements.

Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°-0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibrium and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.

Financial incentives increase fruit and vegetable intake among Supplemental Nutrition Assistance Program participants: a randomized controlled trial of the USDA Healthy Incentives Pilot.

BACKGROUND: US fruit and vegetable (FV) intake remains below recommendations, particularly for low-income populations. Evidence on effectiveness of rebates in addressing this shortfall is limited. OBJECTIVE: This study evaluated the USDA Healthy Incentives Pilot (HIP), which offered rebates to Supplemental Nutrition Assistance Program (SNAP) participants for purchasing targeted FVs (TFVs). DESIGN: As part of a randomized controlled trial in Hampden County, Massachusetts, 7500 randomly selected SNAP households received a 30% rebate on TFVs purchased with SNAP benefits. The remaining 47,595 SNAP households in the county received usual benefits. Adults in 5076 HIP and non-HIP households were randomly sampled for telephone surveys, including 24-h dietary recall interviews. Surveys were conducted at baseline (1-3 mo before implementation) and in 2 follow-up rounds (4-6 mo and 9-11 mo after implementation). 2784 adults (1388 HIP, 1396 non-HIP) completed baseline interviews; data were analyzed for 2009 adults (72%) who also completed ≥1 follow-up interview. RESULTS: Regression-adjusted mean TFV intake at follow-up was 0.24 cup-equivalents/d (95% CI: 0.13, 0.34 cup-equivalents/d) higher among HIP participants. Across all fruit and vegetables (AFVs), regression-adjusted mean intake was 0.32 cup-equivalents/d (95% CI: 0.17, 0.48 cup-equivalents/d) higher among HIP participants. The AFV-TFV difference was explained by greater intake of 100% fruit juice (0.10 cup-equivalents/d; 95% CI: 0.02, 0.17 cup-equivalents/d); juice purchases did not earn the HIP rebate. Refined grain intake was 0.43 ounce-equivalents/d lower (95% CI: -0.69, -0.16 ounce-equivalents/d) among HIP participants, possibly indicating substitution effects. Increased AFV intake and decreased refined grain intake contributed to higher Healthy Eating Index-2010 scores among HIP participants (4.7 points; 95% CI: 2.4, 7.1 points). CONCLUSIONS: The HIP significantly increased FV intake among SNAP participants, closing ∼20% of the gap relative to recommendations and increasing dietary quality. More research on mechanisms of action is warranted. The HIP trial was registered at clinicaltrials.gov as NCT02651064.

Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited).

At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = Te/mec(2) model may be insufficient; we present a more precise model with τ(2)-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of Te measurement relevant to ITER operational scenarios.

Food insecurity among Cambodian refugee women two decades post resettlement.

Resettled refugees have high rates of chronic disease, which may be partially due to persistent food insecurity. This study describes food experiences on arrival in the U.S. and current food security status and examines characteristics related to food insecurity in a well-established refugee community. Focus groups and a survey assessed food security status and personal characteristics of Cambodian women in Lowell, MA, USA. Multivariate logistic regression was used to examine relationships with food insecurity. Current rates of food insecurity are high. In multivariate models, food insecurity was positively associated with being depressed and being widowed, and negatively associated with higher income and acculturation. Early arrivers (1980s) had difficulty in the U.S. food system on arrival, while later arrivers (1990s-2000s) did not. Refugee agencies should consider strategically devoting resources to ensure successful early transition to the U.S. food environment and long-term food security of refugees.

Improvements to the calibration of the MST Thomson scattering diagnostic.

Calibration of the Madison Symmetric Torus Thomson scattering system has been refined to improve temperature fluctuation measurements. Multiple avalanche photodiodes have been directly calibrated for use as reference detectors during calibration, improving accuracy and ease of use. From the absolute calibration we calculate corrections to the gain for variation in detector operating temperature. We also measure the spatial uniformity of detector responsivity for several photodiodes, and present a method of accounting for non-uniformity in the calibration process. Finally, the gain and noise enhancement are measured at multiple wavelengths to improve temperature and uncertainty measurements.

Household food security is inversely associated with undernutrition among adolescents from Kilosa, Tanzania.

Household food insecurity contributes to poor nutritional health, with negative consequences on growth and development during childhood. Although early childhood nutrition needs have received much attention, another important nutritional phase is adolescence. In a sample of 670 adolescents from Kilosa District, Tanzania, this study used 3 approaches to better understand the relationship between food insecurity and undernutrition. First, this study examined the associations between 3 commonly used measures of household food security and undernutrition among 670 adolescents from Kilosa District, Tanzania. The measures of household food security, energy adequacy per adult equivalent, dietary diversity score, and coping strategies index, were strongly correlated with each other and household assets (P < 0.05). Second, this study measured the nutritional status of adolescents in this district, finding a high prevalence of undernutrition (21% with BMI-for-age <5th percentile of the National Center for Health Statistics/WHO reference). Third, this study measured the association between the log odds of undernutrition (as the dependent variable) and each of the 3 measures of household food security. In separate models, household energy adequacy per adult equivalent and household dietary diversity score were inversely associated with undernutrition after adjusting for gender, age, puberty, and the interaction between age and puberty. By contrast, a greater use of coping strategies was not associated with undernutrition. Strategies focused on increasing household energy intake and improving dietary diversity among the most vulnerable households could improve the nutritional health of adolescents.

Acculturation, education, nutrition education, and household composition are related to dietary practices among Cambodian refugee women in Lowell, MA.

Refugees in the United States have higher rates of some chronic diseases than US-born residents or other first-generation immigrants. This may be partially a result of dietary practices in the United States. There is limited information about which factors are related to dietary practices in refugee populations, particularly those who have been in the United States for 10 to 20 years. Research with Cambodian communities may be useful for examining the relationship between refugee characteristics and dietary practices. Two focus groups (n=11) and a survey (n=150) of Cambodian refugee women were conducted in Lowell, MA, from 2007 to 2008. χ(2) analyses, t tests, and analysis of variance tests were used to describe differences in dietary practices (24-hour recall and a targeted qualitative food assessment) by group characteristics. Higher acculturation was related to higher likelihood of eating brown rice/whole grains, and to lower likelihood of eating high-sodium Asian sauces. Higher education was related to higher likelihood of eating vegetables and fruits and to eating white rice fewer times. Nutrition education and receiving dietary advice from a health care provider were related to higher likelihood of eating whole grains/brown rice. Having a child at home was related to a higher likelihood of eating fast food. Among Cambodian refugees who have been in the United States for 10 to 20 years, dietary practices appear to have a relationship with acculturation (positive association), the interrupted education common to refugees (negative association), nutrition education from either programs or health care providers (positive association), and having a child at home (negative association).

Pulse-burst laser systems for fast Thomson scattering (invited).

Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to "pulse-burst" capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned.